Articulated metal forming tool



Jan. 3, 1956 Filed Dec. 20, 1951 E. E. JCNES ARTICULATED METAL FORMING TOOL 2 Sheets-Sheet 1 IN V EN TOR.

EVERETT E. JONES ATToRMEy Jan. 3, 1956 E. E. JONES ARTICULATED METAL FORMING TOOL 2 Sheets-Sheet 2 Filed Dec. 20, 1951 Fir-, 5

Ar ran lvEy United tates. aten Everett E. Jones, Wichita, Kans., assignor to BoeingAirplane Company, Wichita, Kans., a corporation of Delaware Application December 20, 19 51, SerialNo. 262,511

6 Claims. 01.153 32 This invention relates generally to the art of metal forming, and more particularly to the stretch-wrap forming of elongated strips of metal with the aid of a conventional stretch-wrap press. Generally speaking, this type of metal forming is old and well known. As is commonly known, the stretch-wrap press is amachine which includes two opposed jaws capable of gripping the opposite ends of a strip of metal, and capable of being forcibly moved in various directions, under control of the operator, to contemporaneously stretch and wrap a strip of metal around and against the convex surface of a fixed forming die. i

The novelty in the instant invention resides in the provision of a die and a cooperating tool which, with the aid of a conventional stretch press, are capable of producing channel or angle section finished parts which are arced in the plane of their webs. Such apparatus makes it possible to accurately stitch-wrap form channel section body frame parts for aircraft, for instance, a result which numerous aircraft manufacturers throughout this country have sought for at least the past ten years.

More specifically it is an object of this invention to provide a tool in the form of an elongated articulated metal forming filler, hereinafter called a snake, which is made up of preformed sections of solidmaterial the composite shape of which enables thetool to seat against the web and flanges of the desired finished part, together with one form of cooperating die to enable the snake to accurately form an elongated metal stripof channel or angle cross section.

A further object is to provide a method of fabricating such a snake or forming tool. 'In this connection, it should be understood that the tool isa separate article of manufacture and will be sold independent of any type of die with which it will ultimately be used. Furthermore, it should be understood that the manufacturer who desires to form such parts as above mentioned, may also desire to fabricate this particular type of snake or forming tool in his own plant, and may design his own dies with which such tool will be used.

The invention, together with other objects attending its production and use, will be more clearly understood when the following description is read in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view illustrating the forming tool or snake seated in a channel section metal strip to be formed, and a preferred type of cooperating forming die, and illustrates the manner in which the metal strip is stretch-wrapped around the die to form a desired finished part.

Fig. 2 is a perspective view of the snake or forming tool which is an essential part of my invention, the tool being shown in its normal shape prior to being seated in a metal strip to be formed;

Fig. 3 is a perspective view of a finished part formed by the snake and die; 1 I Fig. 4 is a fragmentary vertical section through the connection with the strip to be formed shown seated against the forming edge of the die;

Figs. 5 and 6 are plan views illustrating successive steps in the fabrication of a snake or forming tool in accordance with my invention; 7

Figs. 7 and 8 are transverse sectional views taken along the lines 77 and 8-8, respectively, of Fig. 6.

Fig. 9 isa plan view of a filler plate or plug used in fabrication of the snake of this invention; i

Fig. 10 is a fragmentary plan view of the snake showing additional steps in its fabrication, together with details of construction, certain portions being cut away and shown in section for clarity;

Fig. 11 is'a transverse sectional viewtaken along the line 11-511 of Fig. 10; and

Fig.12 is a fragmentary sectional view of the snake after it has been completely fabricated and straightened for insertion into a linear metal strip to be formed,

Method of fabricating snake or forming tool The first step in the method of fabrication of the snake is to preshape a solid block of material 14 so that it will seat against the interior surfaces of the part to be formed. This shaping step is an important one, and the contours of the shaped block should be held to close tolerence with relation to the contours of. the desired illustrated forming die, with the snake and the metal finished part. The block should also be longer than the part to be formed. If the flange angle of an outer flange of the finished part is to vary from one point to another along the curved contour, then the convex edge of the solid block being shaped should be varied at the desired point or points, as illustrated at 15 in Fig. 8. The block must also be step-cut as at 16 toprovide the desired narrowing of a channel section part to be formed, at the desired point.

The second step in the process is illustrated in Fig. 6. T he step involves the lateral slotting of, one side edge of the pro-shaped block at spaced intervals. This is done by .saw cuts 17, substantially radially disposed, and terminating short of the other side edge. The saw cuts may be more closely spaced along sharp curves, and their spacing may vary throughout the length of the block, depending on the type of section articulating element to be used.

The third step in the method involves milling or otherwise cutting a longitudinal groove 18 into one side surface of the block, the groove intersecting the saw cuts 17 and extending beyond the outermost cuts.

The fourth step is to prepare a plurality of saw cut plugs or plates 19, one for each saw cut, and insert them in the saw cuts, as clearly shown in Figs. 10 and 11.

One of these plates 19 is clearly illustrated in Fig. 9. Each plate is provided with a cut-out or wide slot 29,

the width of which is substantially equal to the thickness of the articulating element to be used. The plates 19 have a double function when placed in the saw cut slots 17. The plate slots 20 are all positioned to register centrally with groove 18, as clearly shown in Fig. 11, and thus serve to receive and hold the articulating element 21 spaced from the opposite side walls of groove 18. In addition, the plates 19 serve to prevent molten metal from escaping when it is poured into groove 18, as will be described below.

The fifth step is to place slotted block 14 on a level surface, groove 18 up, and to position an elongated fixed length flexible member 21 along the bottom of groove 18 and in the slots 20 of plugs 19. This member 21 may be a flexible steel cable, a bicycle type link chain or the like, and ultimately serves as the sole means of joining the separate sections of the tool together, as explained herein below. The member 21 is preferably torque resistant.

The sixth step is the pouring of molten metal into groove 18 and around the member 21, as shown at 22 in Fig. 10. When the metal cools and solidifies member 21 is embedded therein, and is securely locked in groove 18 against movement in any direction with relation to the block 14. To aid in securely locking the metal in the groove 18, holes 23 (Fig. 8) may be drilled laterally into block 14 from the bottom of the groove. The molten metal will then run into these drilled holes and form integral lateral arms which positively prevent displacement of the metal from the groove. Naturally, these drilled holes 23 should be located between the saw cuts 17. Their presence is advantageous but not essential.

The plates 19 are next knocked or otherwise removed from saw slots 17.

The seventh step in the method is the completing of the saw cuts 17 from the opposite edge of block 14, as clearly shown by the dotted lines 24, Fig. 10. The block is thus divided into a plurality of sections interconnected only by the metal 22 in groove 18, and the embedded element 21.

The eighth step is to break or laterally crack the metal 22 along lines which substantially align with saw cuts 17. This may be done by driving wedges 25 (Fig. 10) into the saw cuts 17, from a side edge of the block 14. The crack in the metal is indicated by the numeral 26. This separation of the metal at the saw cuts divides the original shaped block 14 into a plurality of relatively movable individual sections 27 joined together only by the flexible member 21. The limited movement of the sections permits them to be arranged in a straight line, as clearly shown in Fig. 12, so that the entire snake may be seated in a linear channel section strip of metal to be formed, as shown in Fig. 1.

Next, one end section 28 (Fig. 2) and a medial section 29 are each provided with anchor holes 30 and 31, respectively. These holes aid in anchoring the snake against longitudinal movement with relation to the die forming surface during the forming operation, as will be explained in greater detail. This completes the fabrication of the snake tool.

it should be noted that in case a flexible cable is used as the section articulating element 21, there is no need for precise spacing of saw cuts 17. If a link chain is used as element 21, however, the saw cuts should be spaced so that each one intersects the lateral axis of one chain joint, as clearly shown in Fig. 19. Thus when the metal 22 is cracked along saw slots 17, each respective intersected chain joint will be freed sufiiciently to permit slight movement of the individual sections 27. The block 14 may be provided with drilled holes 32 (Fig. 10), between the saw cuts 17. Steel dowel pins 33 may then be driven into holes 32 to pass between two adjacent joints of the chain. If holes 32 are properly spaced with relation to the dimensions of the chain links, if the dowel pins 33 are of a diameter to snugly enter the space between two chain joints, and if the chain joints are properly located with relation to the saw slots 17, then perfect articulation of the individual sections is obtained after the solidified metal 22 is cracked at the specified locations. Dowel pins 33 additionally serve to reinforce the poured metal 22, and to positively lock the individual sections of metal 22 in the grooves of the individual sections of the snake.

it will be understood that the above described method of fabrication produces a forming tool made up of a plurality of preshaped individual sections joined together for limited movement in a common plane, and capable of seating perfectly against the inside surface of the part to be formed, yet also capable of seating in a linear strip of metal to be formed.

A preferred form of die for use in connection with the above described tool includes a heavy plate 34 having one edge 35 shaped to the desired configuration of the inner edge of the finished part. The thickness of the forming edge of plate 34 should be substantially the same as the thickness of the sectional snake, above described. Guide plates 36 and 37 are secured to opposite surfaces of plate 34 in parallel relation, and project outward beyond the forming edge thereof a distance slightly greater than the width of the articulated forming snake, as clearly shown in Fig. 4.

One of the plates, 36, is provided with one or more properly located snake anchoring holes 38 and 39. These holes must be located to register with holes 30 and 31 in the snake tool when the snake is seated along the forming surface of the die in the exact position it will occupy at the completion of the forming operation. If preferred the holes in the die may be drilled first, the snake properly positioned along the die edge, and the registering holes then drilled on into the snake sections. An anchor pin 40 of a diameter to snugly seat in holes 30, 31, 38 and 39 completes the die assembly.

The forming operation One manner of using the above described apparatus is illustrated in drawing Fig. l, which shows a channel section metal strip 42 ready to be formed. The strip to be formed should be longer than the snake so that there is ample stock beyond the opposite ends of the snake for the work sheet to be gripped in the jaws 44, of the stretch wrap machine, as shown. After the snake has been seated inside the work strip, the two are inserted together between the plates 36 and 37 near the anchor end of the die. Pin 40 is inserted through hole 39 in the upper guide plate 36 and into hole 30 in one end section of the snake.

To facilitate firm gripping of the opposite ends of the work strip 42 by the jaws 44, 45, pre-shaped filler blocks 41 and 43 may be seated in the extreme ends of the strip. In the forming operation now being described the holding jaw 44 may be a stationary one, while the jaw 45 must be capable of moving in various directions. Often times the jaws 44 and 45 are made with removable work strip gripping elements which are shaped to the exact cross sectional shape of the work strip to be formed. In such case the filler blocks 41 and 43 are, of course, unnecessary.

After the ends of the work strip have been firmly secured in jaws 44 and 45, the jaw 45 is moved under control of the operator generally along the path defined by the arrows and into the dotted line position, Fig. l. The initial jaw movement places the work strip in tension, and this tension is gradually increased as the strip is wrapped around the forming edge of the die. Since the thickness of the snake is virtually the same as the spacing between the guide plates 36 and 37, the snake prevents the web or horizontal portion of the work strip from buckling. The outer edge of the snake forces the outside flange of the work strip to assume the desired contour, and the inside edge of the snake forces the inside flange of the work strip against the forming edge of the die 34. After the jaw 45 has moved to the dotted line position shown in Fig. 1, it is moved outward to place the work strip under additional tension. This sets the strip and eliminates spring back.

Tension is then released, the work strip is removed from the jaws and from the die, the snake is removed, and the work strip is properly trimmed to produce the finished part, as shown in Fig. 3. This one jaw stretch-wrap forming operation, above described, is preferred when tion of the die edge, and snake anchor pin 40 is inserted through hole 38 in plate 36, into hole 31 of intermediate snake section 29. Jaws 44 and 45 then grip opposite ends of strip 42 and both jaws are moved to stretch and wrap the work strip into contact with the die forming surface between plates 35 and 37.

Having described the apparatus which constitutes this invention, the forming snake in particular, the method of fabricating the snake, and the method of using the apparatus, all with sufiicient clarity to enable those familiar with this art to practice the invention, I claim:

1. As a new article of manufacture, an articulated com posite tool for aid in bending and shaping linear metal strips of channel and angle section in the planes of their webs, comprising: a plurality of cooperating pre-contoured solid block-like sections an'anged end to end in closely spaced relation; a groove in each block-like section, all said grooves being disposed end to end; a nonelongatable elongate flexible metal member seated in and extending lengthwise through the grooves in all said sections; and solidified poured metal filling the groove of each section and embedding and holding a portion of said flexible member rigidly in each of said sections, those portions of the flexible member between the adjacent ends of each adjacent pair of said block-like sections serving to connect all sections together while permitting limited relative movement with respect to adjacent sections.

2. The tool described in claim 1, in which each blocklike section is provided with an angularly disposed drilled hole which communicates with the said groove in that section, and into which the poured metal extends to positively anchor the solidified body of poured metal in the respective sections.

3. The tool described in claim 1 in which the flexible metal member is highly resistant to torsion.

4. The tool described in claim 1 in which the flexible metal member is a length of bicycle type link chain with connecting pins of adjacent links being located between adjacent ones of the block-like sections.

5. The tool described in claim 1 in which certain ones of said block-like sections are provided with anchor pin receiving holes extending entirely through the respective certain sections.

6. As a new article of manufacture, a tool for arcuately forming linear strips of metal having channel and angle cross sections, comprising; a plurality of cooperating similarly arcuate solid elongated sections arranged end to end in closely spaced relation to form an elongated composite body having a cross sectional shape to seat within the channel of a linear channel section part to be formed arcuately in the plane of its web; a length of bicycle-type link chain extending through all said sections, the links of said chain being connected together by pivot pins, one pivot pin being disposed between each adjacent pair of said sections; a cast material rigidly carried by each section and completely encompassing those portions of the chain which extend through the respective sections, said cast material thus serving to rigidly secure the chain to the respective sections.

References Cited in the file of this patent I UNITED STATES PATENTS 406,992 Burgoin July 16, 1889 1,534,314 Heintz Apr. 21, 1925 1,599,947 Bishop Sept. 14, 1926 1,683,572 Mueller et al. Sept. 4, 1928 1,756,448 Bigney Apr. 29, 1930 1,856,597 Stjarnstron May 3, 1932 2,143,442 Kellogg Ian. 10, 1939 2,384,800 Cox Sept. 18, 1945 2,422,500 Poliacek June 17, 1947 2,431,173 Hawkes Nov. 18, 1947 2,451,717 Check Oct. 19, 1948 2,459,132 Nielsen Jan. 11, 1949 FOREIGN PATENTS 145,857 France "Nov. 15, 1881 97,607 Sweden Dec. 12, 1939 

